Planting in Shallow Soil Over Concrete: Options for Zone 6

Question: I have a 20x3 ft area along a driveway and house with only 4 inches of soil over an old concrete slab. What can I plant that doesn't need deep roots? I'd like a flowering hedge.

Reality Check

Four inches isn't enough for shrubs—winter kill is likely, summer watering will be a nightmare, and tall plants may topple. Even perennials and annuals will struggle. Also, the slab may hold water.

Solutions

• Build a retaining wall along the driveway at least 12 inches high to achieve 16+ inches of soil depth.
• If that's not possible, plant drought-tolerant groundcovers like sedum (choice depends on sun exposure).